A34 Wolvercote Viaduct Replacement, United Kingdom

The Wolvercote Viaduct is a major structure on the A34 dual carriageway trunk road, which runs from the A6042 in Salford to Winchester in Hampshire via Oxford, Birmingham and Manchester. The road is one of the most important routes for the carrying of freight from the container port of Southampton to the Midlands. The existing Wolvercote Viaduct carries the A34 (Oxford Western Bypass) over the River Thames flood plain, the Oxford to Birmingham main line railway, the Oxford Canal and the A40 Oxford to Cheltenham road. The Highways Agency had been carrying out remedial work on the 47-year-old viaduct to repair water damage, but in 2006 it reached the conclusion that it would be more cost effective to replace the structure.

Viaduct project

The £44.4m viaduct replacement project began on 6 May 2008 and is set to be completed by 2010. One of the major problems facing the project is that the A34 has to be kept open to traffic for the majority of the time.

In the first phase of the construction project a temporary southbound bridge deck will be built to the east of the old viaduct so that traffic can be diverted while the new viaduct is constructed. This will mean some overnight closures along with the formation of narrow lanes for 500m in both directions throughout the project. The A40 under the viaduct will also have two narrow lanes and temporary peak time traffic lights.

The new viaduct will be in the same position and at the same height as the existing structure and will continue to have two lanes in each direction. Phase 1 will see the construction of a temporary deck southbound to the east of the existing structure; phase 2 will see the existing northbound deck demolished and removed; phase 3 will involve the construction of a northbound deck and the demolition and removal of the existing southbound deck; and in phase 4 the southbound deck will be slid into position and the temporary southbound piers and north abutment will be demolished.

The project will also involve improvements to the south facing slip roads at the Peartree interchange for better access to the A34.

Contract

Tenders were invited for the replacement project in February 2006. In July 2006 Costain Limited, along with Jacobs as the designer, were appointed under the Highway Agency’s Early Contractor Involvement (ECI) initiative to carry out the scheme from planning to construction. Cass Hayward LLP of Chepstow is also part of the ECI contractor team for the project. The project will use durable techniques to minimise future maintenance and also ‘low noise’ tarmac to make the road surface quieter for the nearby residents.

Environmental and remedial work

The existing viaduct is surrounded by a rich landscape and Costain has had to produce a construction environmental management plan which details strict guidelines during the period of construction and also remedial works to restore the landscape. To help blend the viaduct into the surrounding landscape a full planting programme using native species will be carried out, including the reinstatement of any landscape lost during the project. In addition, a drainage system for the viaduct runoff water has been designed that will have minimal environmental impact.